Question: Simplify the following expression: $k = \dfrac{60s}{20s - 20t} + \dfrac{10t - 60s}{20s - 20t}$ You can assume $r,s,t \neq 0$.
Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{60s + 10t - 60s}{20s - 20t}$ $k = \dfrac{10t}{20s - 20t}$ The numerator and denominator have a common factor of $10$, so we can simplify $k = \dfrac{t}{2s - 2t}$